A Tunable Optical Frequency Reference Module Based on a Volume Holographic Bragg Grating

We present a robust and compact micro-integrated, frequency-tunable, optical frequency reference module developed to improve the long-term frequency stability of lasers in quantum technology and satellite laser communication applications. The module is based on a volume holographic Bragg grating (VHBG) and features a multi-level temperature stabilization concept, packaged into a sealed housing with dimensions of$96\,\times \,96\,\times \,35\,\text{mm}^{3}$. The module has a frequency tuning range of more than$\text{65}\,\text{GHz}$with a near-linear behavior. We demonstrate short-term frequency stabilities between$2 \times 10^{5}\,\text{Hz}^{2}/\text{Hz}$and$4 \times 10^{7}\,\text{Hz}^{2}/\text{Hz}$in the Fourier frequency range from$\text{20}\,\text{Hz}$to$\text{200}\,\text{kHz}$, and a minimum overlapping Allan deviation of$\sigma (\tau =1000\,s) = 1.7 \times 10^{-10}$, and$1.5 \times 10^{-9}$over 24$\,$h. The module can also be operated as a wavemeter and spectrometer, yielding residuals below$\text{0.33}\,\text{GHz}$with second-order polynomial regression calibration, and reliably measuring frequency noise PSDs of lasers whose noise exceeds that of the reference module.